No captcha?

Hello,
I am learning programming and just discovered this website. But I am curious, how does it protect its users from spammers (people who post illegal or annoying things) without a reCaptcha? I thought clicking this blue box is required to prove that you are not a robot, can you please share any javascript that you use for this purpose?
Thank you and have a nice day,
Brian

A 21-year old man killed his 19-year old girlfriend because he wanted to get the Mangekyou Sharingan. According to him, he has already awakened his sharingan and now he wanted to get the mangekyou.

To get the mangekyou, a Sharingan user has to lose a loved one, so he decided to kill his girlfriend.